Jack



FIG. 1 is a front view for a jack showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a right-hand side view thereof;

FIG. 4 is a left-hand side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a perspective view thereof; and,

FIG. 8 is a reference mode, during usage thereof.

The broken line showing in FIG. 8 is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a jack, as shown and described. 